I'm having some trouble with my new cfm-tech fuel pressure regulator. I just swapped to a vortec long block which is mostly stock that I will be tuning myself. I had planned on sticking with my stock injectors and turning the fuel pressure up to somewhere in the 20s. After doing some reading I came to understand that I would have trouble tuning out the rich idle from the pressure being so high. My injectors had 230k miles on them so I replaced them with 80# injectors. My problem is that I can't seem to get my pressure lower then 20#'s and believe this to be the cause as to why I cant get my new motor to fire that or my timing is off. I believe my fuel pressure should be down around 14#'s with the 80# injectors with my setup. But basically my main problem is the CFM-Tech regulator with the red **** hits the vacuum line coming out of the back of the TBI not allowing me to back off on the pressure. Has anyone else had a similiar issue with this and what was your solution. I have 2 ideas I could replace the adjustment **** with some kind of bolt or screw but then it would become harder to adjust or I could trim the spring inside my regulator. OR I guess I could reinstall my stock injectors and see how they do but that are really old I don't want to spend another 180$ on new injectors I bought the ones I have so I wouldnt need them later when I installed a bigger cam.

 

Pull the fuel pump fuse so the pump can't run.

Remove and inspect the spark plugs for fouling--clean as required.

Verify that you have spark at all eight plugs. I would also check initial timing.

Start the engine on starting fluid, or aerosol carb cleaner.

If it starts and runs, you've eliminated the ignition as a source of problem. If it still won't start, it's something beyond fuel and spark. Cam timing, lifter preload, etc. A compression test might be wise also.

 

So it should still start if my fuel pressure is actually to high?

 

too much and it may flood. but I think it'd fire still in your scenario

 

Well it was the timing took my time and started at step 1 and readjusted everything. Then it fired up on the first crank of the key. It's running extremely rich though so I need to figure out what I'm gonna do about this regulator.

 

What does the mfg or reg state the range if use is?

top down solutions sells a spring for 15-25 lbs FP for about $15 plus ship.

 

It's a regulator from cfm-tech and they don't state the range of pressure on their website or in the directions. My problems mainly being caused by me not being able to back off of the pressure because the vent line for the map sensor is in the way. I saw a youtube video where the guy bent the vent tube down away from the adjustment **** but I'm a little nervous to try this. All of the parts I ordered from cfm-tech have been quality stuff but as far as getting questions answered from them they have not replied to any of my emails and never answer there phone or return voice mails. They did answer once and said they would call back and they actually did but ever since then I cant seem to get anyone on the phone and ive tried calling all hours of the day.

 

This was in stickies: https://www.thirdgen.org/forums/tbi/...check-out.html

Here is another install: http://z28boy.cz28.com/

 

Still having the same issues. Ok so I bought a regulator rebuild kit and replaced the diaphragm and spring. The new spring is much shorter then my old spring so I figured this would help with my problem. I took the pod off of the throttle body and reinstalled the lines so I could adjust it with the adjustment **** free of the vent line to see if that was the issue. I still cant get the pressure lower then 20psi. I'm running tpi pump so I figured this might of been the problem maybe its to strong for my regulator springs old and the new. I swapped back to my old pump which only has about 6 months of daily driving on it and the highest pressure I could achieve was 10-11 psi. Any suggestions on what I should do to achieve the 14 psi I'm trying to reach.

 

Buy the top down solutions spring. I believe it is the fuel pressure range you desire.

 

Thanks for the advice I just ordered one hopefully this will do the trick. If not I guess i'll be buying a external regulator.

 

TPI pump on my 88 K1500 can be regulated down to stock specs using the stock regulator in the TBI.

Never tried to adjust for higher-than-stock pressure, though.

 

My issue was that I couldn't get it lower then 20 psi with the tpi pump. That's using the stock spring with the cfm tech regulator with brand new fuel lines to. Only thing I could think is that my stock spring is to weak. It was a little rusty and my diaphragm was in bad shape so I replaced both and still the same thing so hopefully this other spring I ordered makes a difference if not that I guess I have to send out my stock injectors to have them cleaned and then run a higher fuel pressure. I hope thats not the case tho because the 454 injectors cost me 180$

 

I actually have a similar problem, stock regulator made adjustable (using this method), TPI pump, 61# injectors and I can't get it to go below 15 psi. I can adjust it from 16 to 15 psi, I have tried a few different stock springs. Blew compressed air through return line to see if clogged.

 

Well the spring I ordered came in today and i'm unfortunately still having the same issue. With the tpi pump I can't get lower then 20 psi. Everything ive read everywhere says the tpi pump is a drop in upgrade for tbi i'm starting to have my doubts. Now im wishing I didnt order these 180$ 454 injectors. I'm running brand new fuel lines but the only thing I can think of is the return line has to many bends in it from the factory and its maybe not bleeding the pressure off fast enough??? I also dont have my cash cap or vent hoses installed on my tank I don't think that would affect anything though but I could be wrong.

 

No wonder fuel pressure for the TPI pump is typically in the 45lbs range, you have the wrong pump.

 

Ive read of plenty of people running even stronger pumps and being able to turn it down to adjust it down to 10 psi? With the hp I will be making and the injectors I have I need the pressure around 14-14.5 psi. I can't get it lower then 20 psi with the tpi pump and cant get it higher then 12 with the tbi pump...

 

It's not his pump. It's the regulator or fuel return plumbing. First Guess: The spring in his regulator is too long, and there isn't enough adjustment in the regulator to remove tension from the too-long spring. 'Course, that's just a guess.

 

When I get home from work today I'm going to try and find a fitting to hook to the return on the tbi so I can plumb a hose to a bucket and see if its my return line giving me issues. As of right not I've tried 3 different springs and they all wouldn't go lower then 20 psi.

 

Can you try to remove gas cap top provide a vent and then check it?

 

Well the beds still off the truck so I still dont have the filler hose/tube that your has cap goes on hooked up to the tank. Does anyone know how much adjustment you can even get out of making a tbi regulator adjustable? And which way your really supposed to adjust it to increase or decrease pressure. Im going counter-clockwise to try and lower the pressure and clockwise to raise it but it doesn't change much but maybe 5 psi between backed all the way out and screwed all the way in unless I go to far in and then it maxes out the gauge to like 60 psi

 

If you coil bind the reg it will blow a gasket. Been there done that.

The top down solutions spring is designed for a GM reg.

You apparently have a restriction. Your test will show that. Are the fittings available at a hardware store in proper size to do an auxillary feed to bucket?

I think my 84 vette return is a 5/16 ID on stock return line. I ran 26 lbs FP last year. Now I am at 21 lbs.

 

Yea I believe its 5/16 I'm gonna take off the fitting that screws into the injector pod when I get home and take it to the hardware store with me hopefully I can fine something to use.

 

return line to TB adapter is 14 mm I believe. I took that off here

http://z28boy.cz28.com/

note link on fuel line info

 

Thanks that helps I doubt any of my local hardware stores have any metric fittings though. I'm gonna have to do some brain storming now.

 

You may end up at a store that serves performance cars. Earls AeroQ Russell may provide the fitting.

 

Yea it looks like I'll have to order everything online If I have to go that route. I'm gonna try blowing out the return line when I get home. The fuel lines are both brand new replacements I ordered off of ebay. Before I installed my new sending unit and pump I drained the tank completely and cleaned out all the crap sitting at the bottom. Yesterday when I swapped the tpi pump back in to see if the spring I ordered worked I noticed alot of black debris sitting at the bottom. I didn't think much of it then but maybe the return line really is clogged. Hopefully this is my problem. After doing some searching on google Ive found a few people with issues similar to mine and it was a clogged return. When I first attempted to start the truck when I had the timing off and it wouldnt start I was actually able to adjust the pressure for a few minutes down to 14 psi where I need it but then It shot up to 20 and has been there ever since. I assumed it was because there was still air in the lines.

 

Well I pretty much solved the problem for the most part I think. The brand new lines weren't clogged but since they're stock aftermarket replacements they're not exactly the same as stock the bends are slightly off and theyre a few inches longer. Installed the lines in the stock locations using my stock clamps and clips but doing this caused the rubber hose on the return line that goes into the fuel sending unit to bend and have a kink in it. Now the lowest the pressure will go is 14-1/2pisi. I think this may be due to the top down solutions spring I installed i'm thinking about installing one of my stock springs to see if it will go a little lower. The only way to know for sure tho would be to plumb something directly off the injector pod into bucket to completely rule out the return line. If the pressure doesnt drop any more when I do that i'll try a different spring if it does I guess I'll be running a new line.

 

I fixed my issue this weekend, just thought I'd let you know. As I said above my fuel pressure was 15-16 psi. During the week I went to the auto wrecker and picked up the upper half of the injector pod. Cleaned it up, put a new diaphram, reused spring, in it that I had from a TBI rebuild kit and made the stock FPR adjustable using the method in my other post. I also blew out the return line with compressed air and had a helper listen through the gas filler for a steady stream of air. Before installing the "rebuilt" regulator assembly I dialed the FPR all the way down. Upon install I instanly had 10 psi. I have a feeling the spring and diphram were the things at fault. I only replaced the upper injectgor pod because I could build it up on the bench before installing it on the car.